1. Field of the Disclosure
Aspects of the present disclosure are directed to an actuator assembly and, more particularly, to an actuator assembly and associated apparatuses implementing an actuatable member configured to change in dimension in response to an actuation signal so as to provide a linear actuation.
2. Description of Related Art
Once a dishwasher has completed a wash/rinse portion of a dish cleaning cycle, the user may be able to optionally select that the dishwasher actively dry the dishware before the dish cleaning cycle is completed. In this manner, the user may desire that the dishware be substantially dry prior to removal thereof from the dishwasher. In order to accomplish such active drying, the dishwasher may include a provision for air circulation within the tub portion, wherein the circulated air may be from within the tub portion, outside the tub portion, or a combination of both. In accomplishing such air circulation, some dishwasher may include a fan, which is normally off during the washing/rinsing portion of the dish cleaning cycle, in combination with a damper in communication between the interior of the tub portion and the exterior of the dishwasher. The damper is normally closed during the washing/rinsing portion of the dish cleaning cycle. Once the washing/rinsing portion of the dish cleaning cycle is completed (and the active drying option is selected), an actuator, such as a solenoid linked to the damper, is actuated to move the damper to an open position. With the damper in the open position, outside air may be allowed to enter the tub portion of the dishwasher. After the damper is opened (and/or detected to be in the open position), the fan is actuated to pull air through the open damper from outside the dishwasher and to circulate the air into the tub portion and about the dishware to facilitate drying of such dishware. De-actuation of the actuator, following de-actuation of the fan, returns the damper to the normally-closed position.
However, in such a configuration, the solenoid (actuator) used to open the damper may, in some instances, experience or cause a power surge upon actuation by an electrical source. In some configurations, the electrical source may be a 12 volt electrical source, since a component (i.e., solenoid) having such a relatively lower voltage input may not require, for example, expensive safety verifications and/or certifications often involved with a component having a relatively higher voltage input (i.e., 120 VAC). One shortcoming with such a configuration, though, is that a power surge may sometimes be associated with the actuation of a 12 volt solenoid, wherein such a power surge may undesirably cause a transient that may be difficult to filter out of the low voltage electrical system. Another shortcoming may be that, since the solenoid may be required to remain actuated to, for example, keep the damper in the open position during the drying procedure, the continuously actuated solenoid (actuator) may undesirably consume excessive power. Yet another shortcoming may be that, since the solenoid may be configured to produce a magnetic field for moving a plunger, and since the generated magnetic field produced by an actuated solenoid may, in turn, cause a relatively rapid movement of the plunger, contact between the plunger and a mechanical stop for limiting travel of the actuated plunger, may undesirably cause significant or otherwise noticeable noise.
In the alternative, the actuator may, in some instances, comprise a wax motor for providing the desired component movement (i.e., moving the damper to the open position). Such a wax motor may include three principal components: 1) a block of wax; 2) a plunger bearing on the wax; and 3) a heat source (i.e., a PTC thermistor) for heating the wax. When the heat source associated with the wax motor is actuated, the wax block is heated and expands. In so expanding, the expanding wax drives the plunger outwardly therefrom and, as such, may provide a linear force/motion for moving a mechanical component engaged with the plunger. Conversely, when the heat source is de-actuated, the wax block cools and contracts and the plunger is accordingly withdrawn. In some instances, withdrawal of the plunger may be facilitated by a biasing force externally applied to plunger or applied from within the wax motor. Depending on some factors such as, for example, the particular application of the wax motor, the plunger implemented by a wax motor may be characterized by a smooth and controlled (i.e., damped) motion, and thus less operational noise as compared to a magnetic solenoid. However, such wax motors may sometimes be unreliable in the field or otherwise have a limited service life.
Further, some dishwashers may include more than one operational component implementing or otherwise requiring linear actuation, wherein such linear actuation may be provided by an appropriate magnetic solenoid and/or a wax motor. Such operational components may include, for example, the actuatable fan damper, an actuatable water valve, an actuatable detergent dispenser, and an actuatable vent device. However, the use of multiple linear actuators, whether magnetic solenoids or wax motors, may undesirably add, for example, cost, higher power consumption, unreliability, and noise to the dishwasher itself.
As such, there exists a need for an actuator device for reducing, for example, cost, power consumption, unreliability, and noise, in a dishwashing appliance, as an alternative to magnetic solenoids and wax motors that may be implemented in such applications.